Exploring the impacts of topography on characteristics of urban road network: A global empirical analysis

Abstract

Although a rough terrain surface can constrain the growth of urban road networks, a comprehensive analysis of the relation between topography and urban road networks is limited. We selected 100 cities around the globe as the study area, and further analyzed the relationship between 10 topographic metrics (representing terrain roughness and natural obstacles) and four road network characteristics (geometric and structural fractal dimensions, circuity, and orientation entropy). The empirical results revealed that the terrain roughness and water area imposed significant negative effects on geometric fractal dimension and positive effects on circuity. The mountain area was positively correlated with the orientation entropy of road networks due to their complex forms. Topographic metrics did not correlate with the structural fractal dimensions of road networks. All topographic metrics could explain 37.2 % and 31.5 % of the variance of geometric fractal dimension and circuity, respectively. At the block level, the correlations between topographic metrics and geometric fractal dimension/circuity were generally similar to those at the city level, but the magnitudes of the correlation coefficient were relatively smaller. These results enhanced our understanding of how topography affects the urban road network from a multi-scale perspective.